$ git clone -n https://src.fedoraproject.org/rpms/firebird.git /var/lib/mock/f40-build-2235632-53445/root/chroot_tmpdir/scmroot/firebird
Cloning into '/var/lib/mock/f40-build-2235632-53445/root/chroot_tmpdir/scmroot/firebird'...
$ git fetch origin f4a59a8e8cbc9f022de671d8ccaf8b0ea47252d3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/firebird
 * [new ref]         f4a59a8e8cbc9f022de671d8ccaf8b0ea47252d3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4a59a8 Update to 4.0.4 (#2247832)